(1) Field of the Invention
The present invention pertains to a conductive spring current path for a warning light. More specifically, the present invention pertains to an electric current path for a warning light typically employed on emergency vehicles where the warning light is oscillated through an arc segment. The conductive circuit that provides power to the warning light includes a spring that is connected between a stationary base of the warning light and an oscillating assembly of the warning light.
(2) Description of the Related Art
A standard prior art emergency vehicle warning light comprised a sealed beam lamp in which a light bulb and a reflector were integrally assembled. The warning light would be mounted to the emergency vehicle by a bearing assembly that enabled the sealed beam lamp to rotate. A motive source would be provided to rotate the sealed beam lamp. The electric current that provided power to the lamp would typically employ a conductive slip ring and a carbon brush that would slide along the slip ring as the lamp is rotated. The return current path from the lamp would typically pass through the bearing assembly.
These prior art emergency vehicle warning lights were disadvantaged in that they required large currents to illuminate the lamps. In addition, the carbon brushes that would slide along the conductive slip rings of the lamps would wear over time and require frequent replacement. The carbon brushes sliding on the conductive slip rings would also produce a dirty, abrasive dust that could interfere with the operations of the warning lights. The high currents returned through the bearing assemblies of the lights also degraded the bearing lubricant as the result of electrical arcing that would occur in the bearing assembly.
The subsequent development of the halogen light capsule led to the development of modern emergency vehicle warning lights in which a parabolic reflector is rotated around or oscillated adjacent a hardwired, stationary lamp to create a flashing signal. More recently, emergency vehicle warning light assemblies have been developed in which the light source is permanently or semi-permanently attached to the reflector. These warning light assemblies had the advantages of being small, higher performance assemblies that could be manufactured, and in some cases, permanently focused by computer-controlled robotic assemblers.
Still newer emergency vehicle warning light sources, for example LED""s with integral lens optics or reflectors, provide further improvements to emergency vehicle warning lights, including oscillating warning lights. However, a persistent problem in the design of oscillating warning lights is providing a reliable, maintenance-free circuit path that supplies electric energy to the moving light source. Oscillating lights generally operate at a rate of 100 cycles per minute. This rate of oscillation has required a more complex circuit path to supply electric power to the oscillating light assembly which increases its manufacturing costs.
The oscillating emergency vehicle warning light of the present invention is basically comprised of a light assembly that is mounted on a stationary base by a pivot mount. The pivot mount enables the light assembly to rotate or pivot about an axis of the pivot mount relative to the base. A motive source is operatively connected to the pivot mount and oscillates the pivot mount and the attached light assembly through an arc segment.
The stationary base can be a part of the emergency vehicle with which the warning light is used, or can be a separate component part attached to the emergency vehicle.
The pivot mount is comprised of a bearing assembly that has a hollow shaft at its center. The hollow shaft is mounted stationary to the base and a bearing sleeve is mounted for rotation on the exterior of the hollow shaft. (Note: The bearing could be stationary with the hollow shaft attached to the oscillating element.)
The light assembly is mounted to the bearing sleeve of the bearing assembly. The light assembly comprises a mounting bracket that is secured to the bearing sleeve for oscillating movement with the bearing sleeve. An optical source, including a light source and a lens optic or reflector, are mounted on the mounting bracket for oscillating movement with the mounting bracket.
The motive source is connected through a drivewheel with the bearing sleeve. The motive source oscillates the drivewheel and thereby oscillates the bearing sleeve and the attached mounting bracket of the light assembly.
The electrical circuit of the invention provides a resilient electrical connection to the oscillating light assembly that is capable of withstanding the many oscillating cycles of the light assembly during the useful life of the warning light. The circuit comprises a power wire that is operatively connected to a source of electric power. The power wire is secured to the stationary base. A ground wire, also operatively connected to the source of electric power, is also secured to the stationary base. The novel features of the electrical circuit connect the stationary power wire through the oscillating light assembly to the stationary ground wire to complete the circuit through the light assembly.
In a first embodiment of the novel electrical circuit, the circuit includes a spiral spring having a length with opposite first and second ends and a center axis. The length of the spring is positioned in a single plane and spirals around the axis of the spring. The axis of the spring extends through the hollow shaft of the pivot mount. One end of the spiral spring is operatively connected to the stationary power wire and the opposite end of the spiral spring is operatively connected to a portion of the electrical circuit that oscillates with the light assembly. The return path of the electrical circuit from the light assembly passes through the bearing assembly to the ground wire connected to the stationary base.
A second embodiment of the electrical circuit employs a coil spring having a length with opposite first and second ends and a center axis. The length of the coil spring coils around the spring axis. The coil spring extends through the hollow shaft of the pivot mount. One end of the coil spring is operatively connected to the power wire secured stationary relative to the base and the opposite end of the coil spring is operatively connected to a portion of the electrical circuit that oscillates with the light assembly. The electrical circuit returns from the light assembly through the bearing assembly to the ground wire secured to the stationary base.
In both embodiments of the circuit, the spring provides a flexible leg in the circuit that can operate for many cycles of the light assembly without requiring maintenance.